html,body{
  margin: 0;
  font-weight: lighter;
}

.contentbox{
  position: absolute;
  width: 50%;
  left: 37.5%;
  right: 12.5%;
}

.content{
  font-size: 1.1em;
  line-height: 1.7em;
  margin-top: 10px;
}

h1,h2,h3,h4,h5,h6{
  font-weight: inherit;
  margin-top: 15px;
  margin-bottom: 15px;
}

iframe{
  width: 100%;
  height: 600px;
}